April 22, 2010 AT 10:24 am

EARTH DAY – Voltaic DIY Solar, how to solar charge an iPad #earthday

We test-charged an iPad with our solar backpack and it worked, but with two caveats: 1) The iPad charges from a USB port like a phone, but its battery is 25 Watt hours (about 5x that of an iPhone), so charging the iPad will take about 5x as long. 2) You’ll need to put the iPad into sleep mode for it to charge.

This is not a bug in our charger, it is due to the size of the battery and the charge circuitry within the iPad. Since the iPad has such a large battery, it is designed to charge best off a wall charger or high-powered USB port found on a Mac and some other computers. If you plug it into a normal USB port on a PC, you’ll get 2.5 Watts instead of the 10 Watts or more you get from a high-powered USB port.

If you want to solar charge your iPad from one of our Backpacks, you should plan on plugging it into a full Voltaic battery at night or at a time time when you’re not planning to use the device. We are going to do more testing, but it took us an hour to get from 77% to 83% charge.

You might also want to carry a spare battery as it will take about 3 full Battery Pack V11s to fully charge the iPad.

The other option is to use our Generator battery, which outputs 2Amps / 10 Watts and will appear more like a wall outlet to the iPad, although we currently out of stock.

Update: A customer using our earlier Silver JetPack battery (14.4 Watt hours capacity) reports going from 38% full to 81% in three hours. He did put the iPad into sleep mode before charging.

Celebrate Earth Day 2010 with Adafruit – we’ll have posts all day and night with fun power/earth/green related projects and we’re having a one-time only sale on solar panels! Get a 2W solar panel 6V, 330mA out for $20, today only!

"When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you" - Pablo Picasso